This invention relates to indexable head diamond dressers and more particularly to an improved means for maintaining the concentricity of the mounted diamond with the axis of the shank portion of the cutting tool. Indexable head diamond dressing tools are known in the prior art and are designed to equalize wear on the diamond cutting element. See for example U.S. Pat. Nos. 2,587,132; 2,761,441; 2,999,493; and 3,452,735. Diamond cutting tools of this type have a tool holding member rotatably cooperating with a supporting shaft. Resilient means urge the two members into tight frictional engagement. The tool holding member may be rotated upon the application of a torque sufficient to overcome the forces holding the tool holding member in its rotative position on the shaft. The use of a rotatable tool holding member eliminates the need for removing the shaft portion from its mounting when a fresh cutting surface portion of the mounted diamond must be positioned for use.
The prior art devices have not, however, eliminated the problem of lateral shifting of the tool holding member with respect to the shaft axis. Previous designs rely on the accuracy and closeness of the fit between the rotating members. After a period of use, however, the confronting surfaces will wear to a degree which will permit the tool holding member to shift radially with respect to the supporting shaft axis with the result that the concentricity of the diamond point with the shaft axis is no longer true. This is a particularly serious problem when, for example, tracer devices which allow no deviation from predetermined datum dimensions are used. In such a device a diamond ground to a specific conical point is mounted concentric with the supporting shaft axis and is required to maintain its original datum point throughout repeated operations. Accurate concentricity of this magnitude cannot be maintained merely by urging rotating member confrontation surfaces such as those disclosed in the prior art together with resilient means. Wear will still result in loss of the diamond point's concentricity with the shaft axis.